简介：OkHttp是一个默认有效的HTTP客户端，有效地执行HTTP可以加快您的负载并节省带宽，如果您的服务有多个IP地址，如果第一次连接失败，OkHttp将尝试备用地址。这对于IPv4 + IPv6和冗余数据中心中托管的服务是必需的。OkHttp启动具有现代TLS功能（SNI，ALPN）的新连接，并在握手失败时回退到TLS 1.0，OkHttp支持Android 2.3及更高版本。对于Java，最低要求是1.7。

操作步骤：

1、创建OkhttpClient。

2、mClient执行newCall将Request转化成一个Call。

3、最后call执行excute同步执行，enqueue异步执行。

4、Request主要通过Request.Builder来构建。

5、缓存。

6、取消请求。

导包

<!--okhttp3-->
        <dependency>
            <groupId>com.squareup.okhttp3</groupId>
            <artifactId>okhttp</artifactId>
            <version>4.9.1</version>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.5</version>
        </dependency>

GET请求

get无参

/**
     * 以get方式调用第三方接口
     * @param url
     */
    public static void doGet1(String url) throws IOException {
        OkHttpClient okHttpClient = new OkHttpClient();
        final Request request = new Request.Builder()
                .url(url)
                .get()//默认就是GET请求，可以不写
                .build();
        Response response = okHttpClient.newCall(request).execute();
        String string = response.body().string();
        System.out.println(string);

    }

get有参

public static void doGet2(String url, Map<String, Object> paramMap) throws IOException {
        OkHttpClient okHttpClient = new OkHttpClient();
        Request.Builder requestbuilder = new Request.Builder()
               .get();//默认就是GET请求，可以不写
        
        StringBuilder urlbuilder = new StringBuilder(url);
        if (Objects.nonNull(paramMap)) {
            urlbuilder.append("?");
            paramMap.forEach((key, value) -> {
                try {
                    urlbuilder.append(URLEncoder.encode(key, "utf-8")).append("=").append(URLEncoder.encode((String) value, "utf-8")).append("&");
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            });
            urlbuilder.deleteCharAt(urlbuilder.length() - 1);
        }

        Request request = requestbuilder.url(urlbuilder.toString()).build();
        Response response = okHttpClient.newCall(request).execute();
        String string = response.body().string();
        System.out.println(string);

    }

get带参数和请求头

  /**
     * 以get方式调用第三方接口
     * @param url
     */
    public static void doGet3(String url, Map<String, Object> paramMap,Map<String, String> heardMap) throws IOException {
        OkHttpClient okHttpClient = new OkHttpClient();
        Request.Builder requestbuilder = new Request.Builder()
                .get();//默认就是GET请求，可以不写

        //增加参数
        StringBuilder urlbuilder = new StringBuilder(url);
        if (Objects.nonNull(paramMap)) {
            urlbuilder.append("?");
            paramMap.forEach((key, value) -> {
                try {
                    urlbuilder.append(URLEncoder.encode(key, "utf-8")).append("=").append(URLEncoder.encode((String) value, "utf-8")).append("&");
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            });
            urlbuilder.deleteCharAt(urlbuilder.length() - 1);
        }
        //增加请求头
        Request.Builder heardBuilder = requestbuilder.url(urlbuilder.toString());
        for (Map.Entry<String, String> stringObjectEntry : heardMap.entrySet()) {
            heardBuilder.addHeader(stringObjectEntry.getKey(),stringObjectEntry.getValue());
        }

        Request request = heardBuilder.build();
        Response response = okHttpClient.newCall(request).execute();
        System.out.println(response.body().string());
        System.out.println(response.message());
        System.out.println(response.code());

    }

get请求 换种方式获取结果

/**
     * 以get方式调用第三方接口
     * @param url
     */
    public static void doGet(String url,Map<String, Object> paramMap,Map<String, String> heardMap) {
        OkHttpClient okHttpClient = new OkHttpClient();
        Request.Builder requestbuilder = new Request.Builder()
                .get();//默认就是GET请求，可以不写

        //增加参数
        StringBuilder urlbuilder = new StringBuilder(url);
        if (Objects.nonNull(paramMap)) {
            urlbuilder.append("?");
            paramMap.forEach((key, value) -> {
                try {
                    urlbuilder.append(URLEncoder.encode(key, "utf-8")).append("=").append(URLEncoder.encode((String) value, "utf-8")).append("&");
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            });
            urlbuilder.deleteCharAt(urlbuilder.length() - 1);
        }
        //增加请求头
        Request.Builder heardBuilder = requestbuilder.url(urlbuilder.toString());
        for (Map.Entry<String, String> stringObjectEntry : heardMap.entrySet()) {
            heardBuilder.addHeader(stringObjectEntry.getKey(),stringObjectEntry.getValue());
        }

        Request request = heardBuilder.build();
        Call call = okHttpClient.newCall(request);
        call.enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                System.out.println( "onFailure: ");
            }

            @Override
            public void onResponse(Call call, Response response) throws IOException {
                System.out.println(response.body().string());
                System.out.println(response.message());
                System.out.println(response.code());
            }
        });
    }

POST请求

post-json传参

 /**
     * post请求
     * @param url
     * @param json
     */
    public static void doPost(String url, String json, Map<String, String> heardMap) throws IOException {
        MediaType mediaType = MediaType.parse("application/json; charset=utf-8");
        String requestBody = json;
        Request.Builder requestbuilder = new Request.Builder()
                .url(url)
                .post(RequestBody.create(mediaType, requestBody));
        //增加请求头
        for (Map.Entry<String, String> stringObjectEntry : heardMap.entrySet()) {
            requestbuilder.addHeader(stringObjectEntry.getKey(), stringObjectEntry.getValue());
        }

        Request request = requestbuilder.build();
        OkHttpClient okHttpClient = new OkHttpClient();
        Response response = okHttpClient.newCall(request).execute();
        System.out.println(response.body().string());
        System.out.println(response.message());
        System.out.println(response.code());
    }

post-params传参

 /**
     * post请求
     * @param url
     * @param json
     */
    public static void doPost(String url, String json, Map<String, String> heardMap) throws IOException {
        MediaType mediaType = MediaType.parse("application/x-www-form-urlencoded");
        String requestBody = json;
        Request.Builder requestbuilder = new Request.Builder()
                .url(url)
                .post(RequestBody.create(mediaType, requestBody));
        //增加请求头
        for (Map.Entry<String, String> stringObjectEntry : heardMap.entrySet()) {
            requestbuilder.addHeader(stringObjectEntry.getKey(), stringObjectEntry.getValue());
        }

        Request request = requestbuilder.build();
        OkHttpClient okHttpClient = new OkHttpClient();
        Response response = okHttpClient.newCall(request).execute();
        System.out.println(response.body().string());
        System.out.println(response.message());
        System.out.println(response.code());
    }

 /**
     * post请求
     * @param url
     * @param paramMap
     */
    public static void doPost1(String url, Map<String, Object> paramMap,Map<String,String> heardMap) throws IOException {
        FormBody.Builder formBody = new FormBody.Builder();
        if (Objects.nonNull(paramMap)) {
            paramMap.forEach((x, y) -> formBody.add(x, (String) y));
        }
        RequestBody requestBody = formBody.build();
        Request.Builder requestbuilder = new Request.Builder()
                .url(url)
                .post(requestBody);
        //增加请求头
        for (Map.Entry<String, String> stringObjectEntry : heardMap.entrySet()) {
            requestbuilder.addHeader(stringObjectEntry.getKey(), stringObjectEntry.getValue());
        }

        Request request = requestbuilder.build();
        OkHttpClient okHttpClient = new OkHttpClient();
        Response response = okHttpClient.newCall(request).execute();
        System.out.println(response.body().string());
        System.out.println(response.message());
        System.out.println(response.code());
    }

post-表单传参-上传文件

达到类似效果

 public static void doPost2(String url,File file) throws IOException {
        OkHttpClient client = new OkHttpClient();
        RequestBody body = new MultipartBody.Builder()
                .setType(MultipartBody.FORM)
                .addFormDataPart("id", "111")
                .addFormDataPart("content", "{\"do_layout\":1}")
                .addFormDataPart("file", file.getName(), RequestBody.create(MediaType.parse("text/plain"), file))
                .build();

        Request request = new Request.Builder()
                .url(url)
                .post(body)
                .addHeader("x-tilake-app-key", "")
                .addHeader("x-tilake-ca-timestamp", "")
                .addHeader("x-tilake-ca-signature", "")
                .addHeader("Content-Type", body.contentType().toString())
                .addHeader("Accept", "*/*")
                .build();

        try {
            Response response = client.newCall(request).execute();
            System.out.println(response.body().string());
            System.out.println(response.message());
            System.out.println(response.code());
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

提供一个工具类,可以直接使用

package com.example.httpdemo.okhttp;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import lombok.extern.slf4j.Slf4j;
import okhttp3.*;
import org.apache.commons.io.FileUtils;
import org.springframework.web.multipart.MultipartFile;
import java.io.File;
import java.io.IOException;
import java.util.Map;
import java.util.Objects;
import java.util.concurrent.TimeUnit;


@Slf4j
public class OkHttpUtil {

    public static final String MEDIA_TYPE_JSON = "application/json; charset=utf-8";

    private OkHttpUtil() {
    }

    /**
     * 获取默认的OkHttpClient
     * @return
     */
    public static OkHttpClient getOkHttpClient() {
        return getOkHttpClient(60, 60, 60);
    }

    public static OkHttpClient getOkHttpClient(int connectTimeout, int readTimeOut, int writeTimeOut) {
        OkHttpClient.Builder builder = new okhttp3.OkHttpClient().newBuilder();
        builder.connectTimeout(connectTimeout, TimeUnit.SECONDS);
        builder.readTimeout(readTimeOut, TimeUnit.SECONDS);
        builder.writeTimeout(writeTimeOut, TimeUnit.SECONDS);
        return builder.build();
    }

    /**
     * get请求
     * @param okHttpClient
     * @param url
     * @param headers header参数
     * @return
     */
    public static String get(OkHttpClient okHttpClient, String url, Headers headers) {
        log.info("okHttpClient get url:{}.", url);
        Request request = new Request.Builder().url(url).headers(headers).get().build();

        String responseData = request(okHttpClient, url, request);
        log.info("okHttpClient get url:{},request responseData====> {}", url, responseData);
        return responseData;
    }

    public static String get(OkHttpClient okHttpClient, String url) {
        Headers headers = new Headers.Builder().build();
        return get( okHttpClient, url, headers);
    }

    /**
     * GET请求。使用默认的 okHttpClient 和 headers
     * @param url
     * @return
     */
    public static String get(String url) {
        OkHttpClient okHttpClient = getOkHttpClient();
        Headers headers = new Headers.Builder().build();
        return get( okHttpClient, url, headers);
    }

    /**
     * post请求，获取响应结果
     *
     * @param okHttpClient
     * @param url
     * @param bodyJson
     * @param headers
     * @return
     */
    public static String post(OkHttpClient okHttpClient, String url, JSONObject bodyJson, Headers headers) {
        log.info("okHttpClient post url:{}, body====> {}", url, bodyJson);
        MediaType mediaTypeJson = MediaType.parse(MEDIA_TYPE_JSON);
        RequestBody requestBody = RequestBody.create(mediaTypeJson, JSON.toJSONString(bodyJson));
        Request request = new Request.Builder().url(url).headers(headers).post(requestBody).build();

        String responseData = request(okHttpClient, url, request);
        log.info("okHttpClient post url:{},post responseData====> {}", url, responseData);
        return responseData;
    }

    public static String post(OkHttpClient okHttpClient, String url, JSONObject bodyJson) {
        Headers headers = new Headers.Builder().build();
        return post( okHttpClient,  url,  bodyJson, headers);
    }

    /**
     * post请求。使用默认的 okHttpClient 和 headers
     * @param url
     * @param bodyJson
     * @return
     */
    public static String post( String url, JSONObject bodyJson) {
        //使用默认的 okHttpClient
        OkHttpClient okHttpClient = getOkHttpClient();
        Headers headers = new Headers.Builder().build();
        //如果需要自定义 okHttpClient或headers传参，可以调用以下方法
        return post( okHttpClient,  url,  bodyJson, headers);
    }

    /**
     * 获取响应结果
     *
     * @param okHttpClient
     * @param url
     * @param request
     * @return
     */
    public static String request(OkHttpClient okHttpClient, String url, Request request) {
        String responseData = "";
        try (Response response = okHttpClient.newCall(request).execute()) {
            if (response != null && response.body() != null) {
                return response.body().string();
            }
        } catch (Exception e) {
            log.error("okHttpClient getResponse error.url:{}", url, e);
        }

        return responseData;
    }

    /**
     * 上传文件
     *
     * @param okHttpClient  okHttp客户端
     * @param url 上传文件的url
     * @param fileKey       文件对应的key
     * @param formDataJson  form-data参数
     * @param headers
     * @param file
     * @return
     */
    public static String uploadFile(OkHttpClient okHttpClient, String url,
                                     String fileKey, File file, JSONObject formDataJson, Headers headers) {
        log.info("uploadFile url:{}, uploadFile formDataJson====> {}", url, formDataJson);
        // 支持传文件的同时，传参数。
        MultipartBody requestBody = getMultipartBody(fileKey, file,  formDataJson);

        // 构建request请求体
        Request request = new Request.Builder().url(url).headers(headers).post(requestBody).build();

        String responseData = request(okHttpClient, url, request);

        // 会在本地产生临时文件，用完后需要删除
        if (file.exists()) {
            file.delete();
        }
        return responseData;

    }

    /**
     * 上传文件
     * @param url
     * @param fileKey form-data文件对应的key
     * @param multipartFile 文件上传对应的 multipartFile
     * @param formDataJson form-data参数
     * @return
     */
    public static String uploadFile(String url,
                                    String fileKey, MultipartFile multipartFile, JSONObject formDataJson) {
        //使用默认的okHttpClient
        OkHttpClient okHttpClient = getOkHttpClient();
        Headers headers = new Headers.Builder().build();
        return uploadFile(okHttpClient, url, fileKey, getFile(multipartFile), formDataJson, headers);
    }

    public static String uploadFile(OkHttpClient okHttpClient, String url,
                                    String fileKey, File file, JSONObject formDataJson) {
        Headers headers = new Headers.Builder().build();
        return uploadFile(okHttpClient, url,  fileKey, file, formDataJson, headers);
    }

    /**
     * 上传文件
     * 使用默认的okHttpClient
     *
     * @param url
     * @param fileKey form-data文件对应的key
     * @param file 文件
     * @param formDataJson form-data参数
     * @return
     */
    public static String uploadFile(String url,
                                    String fileKey, File file, JSONObject formDataJson) {
        //使用默认的okHttpClient
        OkHttpClient okHttpClient = getOkHttpClient();
        Headers headers = new Headers.Builder().build();
        return uploadFile(okHttpClient, url, fileKey, file, formDataJson, headers);
    }

    /**
     * 上传文件用。构建form-data 参数
     *
     * @param fileKey       文件对应的key
     * @param file          文件
     * @param formDataJson  form-data参数
     * @return
     */
    public static MultipartBody getMultipartBody(String fileKey, File file, JSONObject formDataJson) {
        RequestBody fileBody = RequestBody.create(MultipartBody.FORM, file);

        MultipartBody.Builder bodyBuilder = new MultipartBody.Builder();
        // 设置传参为form-data格式
        bodyBuilder.setType(MultipartBody.FORM);
        bodyBuilder.addFormDataPart(fileKey, file.getName(), fileBody);
        // 添加 form-data参数
        for (Map.Entry<String, Object> entry : formDataJson.entrySet()) {
            //参数通过 bodyBuilder.addFormDataPart(key, value) 添加
            bodyBuilder.addFormDataPart(entry.getKey(), Objects.toString(entry.getValue(),""));
        }
        return bodyBuilder.build();
    }

    /**
     * 获取文件
     * @param multipartFile
     * @return
     */
    public static File getFile(MultipartFile multipartFile) {
        File file = new File(Objects.requireNonNull(multipartFile.getOriginalFilename()));
        try {
            FileUtils.copyInputStreamToFile(multipartFile.getInputStream(), file);
        } catch (IOException e) {
            log.error("copyInputStreamToFile error.", e);
        }
        return file;
    }

}